Hi,

I'm just wondering if I'm correct and also what notation I should use here.

The question is asking for the domain and range of

I think the domain is and

Thanks for your help.

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- October 20th 2011, 10:47 PMStroodleDomain and Range
Hi,

I'm just wondering if I'm correct and also what notation I should use here.

The question is asking for the domain and range of

I think the domain is and

Thanks for your help. - October 20th 2011, 11:10 PMDevenoRe: Domain and Range
yes, the domain is a subset of . but in this case, if f(x,y) makes sense for all real numbers x and y,

then the domain**equals**.

now is always positive, so we know the range is a subset of the positive reals. the question is, can

turn out to be any real number? and it can: let's say we have a certain real number r in mind. then we could pick x = 0, and y = r.

so now we ask, given that can be any real number, can be any positive real number?

suppose s is positive. then ln(s) makes sense, so we can pick (x,y) = (0,ln(s)), and then .

so we see any positive real number is in the range of f, and only positive real numbers are in the range of f.

so range(f) = . this is sometimes also written: or as the interval - October 20th 2011, 11:10 PMSammySRe: Domain and Range
Not sure what your answer is for the Domain: it's all of .

Your Range is correct.

(*Deveno beat me by less than 1 minute.)*